tidb plan_cost 源码
tidb plan_cost 代码
文件路径：/planner/core/plan_cost.go
// Copyright 2022 PingCAP, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package core
import (
"math"
"github.com/pingcap/errors"
"github.com/pingcap/tidb/expression"
"github.com/pingcap/tidb/kv"
"github.com/pingcap/tidb/parser/model"
"github.com/pingcap/tidb/planner/property"
"github.com/pingcap/tidb/sessionctx/variable"
"github.com/pingcap/tidb/statistics"
"github.com/pingcap/tidb/util/paging"
)
const (
// CostFlagRecalculate indicates the optimizer to ignore cached cost and recalculate it again.
CostFlagRecalculate uint64 = 1 << iota
// CostFlagUseTrueCardinality indicates the optimizer to use true cardinality to calculate the cost.
CostFlagUseTrueCardinality
)
const (
modelVer1 = 1
modelVer2 = 2
)
func hasCostFlag(costFlag, flag uint64) bool {
return (costFlag & flag) > 0
}
// GetPlanCost calculates the cost of the plan if it has not been calculated yet and returns the cost.
func (p *basePhysicalPlan) GetPlanCost(taskType property.TaskType, option *PlanCostOption) (float64, error) {
costFlag := option.CostFlag
if p.planCostInit && !hasCostFlag(costFlag, CostFlagRecalculate) {
// just calculate the cost once and always reuse it
return p.planCost, nil
}
p.planCost = 0 // the default implementation, the operator have no cost
for _, child := range p.children {
childCost, err := child.GetPlanCost(taskType, option)
if err != nil {
return 0, err
}
p.planCost += childCost
}
p.planCostInit = true
return p.planCost, nil
}
// GetPlanCost calculates the cost of the plan if it has not been calculated yet and returns the cost.
func (p *PhysicalSelection) GetPlanCost(taskType property.TaskType, option *PlanCostOption) (float64, error) {
costFlag := option.CostFlag
if p.planCostInit && !hasCostFlag(costFlag, CostFlagRecalculate) {
return p.planCost, nil
}
var selfCost float64
switch p.ctx.GetSessionVars().CostModelVersion {
case modelVer1: // selection cost: rows * cpu-factor
var cpuFactor float64
switch taskType {
case property.RootTaskType, property.MppTaskType:
cpuFactor = p.ctx.GetSessionVars().GetCPUFactor()
case property.CopSingleReadTaskType, property.CopDoubleReadTaskType:
cpuFactor = p.ctx.GetSessionVars().GetCopCPUFactor()
default:
return 0, errors.Errorf("unknown task type %v", taskType)
}
selfCost = getCardinality(p.children[0], costFlag) * cpuFactor
if p.fromDataSource {
selfCost = 0 // for compatibility, see https://github.com/pingcap/tidb/issues/36243
}
case modelVer2: // selection cost: rows * num-filters * cpu-factor
var cpuFactor float64
switch taskType {
case property.RootTaskType:
cpuFactor = p.ctx.GetSessionVars().GetCPUFactor()
case property.MppTaskType: // use a dedicated cpu-factor for TiFlash
cpuFactor = p.ctx.GetSessionVars().GetTiFlashCPUFactor()
case property.CopSingleReadTaskType, property.CopDoubleReadTaskType:
cpuFactor = p.ctx.GetSessionVars().GetCopCPUFactor()
default:
return 0, errors.Errorf("unknown task type %v", taskType)
}
selfCost = getCardinality(p.children[0], costFlag) * float64(len(p.Conditions)) * cpuFactor
}
childCost, err := p.children[0].GetPlanCost(taskType, option)
if err != nil {
return 0, err
}
p.planCost = childCost + selfCost
p.planCostInit = true
return p.planCost, nil
}
// GetCost computes the cost of projection operator itself.
func (p *PhysicalProjection) GetCost(count float64) float64 {
sessVars := p.ctx.GetSessionVars()
cpuCost := count * sessVars.GetCPUFactor()
concurrency := float64(sessVars.ProjectionConcurrency())
if concurrency <= 0 {
return cpuCost
}
cpuCost /= concurrency
concurrencyCost := (1 + concurrency) * sessVars.GetConcurrencyFactor()
return cpuCost + concurrencyCost
}
// GetPlanCost calculates the cost of the plan if it has not been calculated yet and returns the cost.
func (p *PhysicalProjection) GetPlanCost(taskType property.TaskType, option *PlanCostOption) (float64, error) {
costFlag := option.CostFlag
if p.planCostInit && !hasCostFlag(costFlag, CostFlagRecalculate) {
return p.planCost, nil
}
childCost, err := p.children[0].GetPlanCost(taskType, option)
if err != nil {
return 0, err
}
p.planCost = childCost
p.planCost += p.GetCost(getCardinality(p, costFlag)) // projection cost
p.planCostInit = true
return p.planCost, nil
}
// GetCost computes cost of index lookup operator itself.
func (p *PhysicalIndexLookUpReader) GetCost(costFlag uint64) (cost float64) {
indexPlan, tablePlan := p.indexPlan, p.tablePlan
ctx := p.ctx
sessVars := ctx.GetSessionVars()
// Add cost of building table reader executors. Handles are extracted in batch style,
// each handle is a range, the CPU cost of building copTasks should be:
// (indexRows / batchSize) * batchSize * CPUFactor
// Since we don't know the number of copTasks built, ignore these network cost now.
indexRows := getCardinality(indexPlan, costFlag)
idxCst := indexRows * sessVars.GetCPUFactor()
// if the expectCnt is below the paging threshold, using paging API, recalculate idxCst.
// paging API reduces the count of index and table rows, however introduces more seek cost.
if ctx.GetSessionVars().EnablePaging && p.expectedCnt > 0 && p.expectedCnt <= paging.Threshold {
p.Paging = true
pagingCst := calcPagingCost(ctx, p.indexPlan, p.expectedCnt)
// prevent enlarging the cost because we take paging as a better plan,
// if the cost is enlarged, it'll be easier to go another plan.
idxCst = math.Min(idxCst, pagingCst)
}
cost += idxCst
// Add cost of worker goroutines in index lookup.
numTblWorkers := float64(sessVars.IndexLookupConcurrency())
cost += (numTblWorkers + 1) * sessVars.GetConcurrencyFactor()
// When building table reader executor for each batch, we would sort the handles. CPU
// cost of sort is:
// CPUFactor * batchSize * Log2(batchSize) * (indexRows / batchSize)
indexLookupSize := float64(sessVars.IndexLookupSize)
batchSize := math.Min(indexLookupSize, indexRows)
if batchSize > 2 {
sortCPUCost := (indexRows * math.Log2(batchSize) * sessVars.GetCPUFactor()) / numTblWorkers
cost += sortCPUCost
}
// Also, we need to sort the retrieved rows if index lookup reader is expected to return
// ordered results. Note that row count of these two sorts can be different, if there are
// operators above table scan.
tableRows := getCardinality(tablePlan, costFlag)
selectivity := tableRows / indexRows
batchSize = math.Min(indexLookupSize*selectivity, tableRows)
if p.keepOrder && batchSize > 2 {
sortCPUCost := (tableRows * math.Log2(batchSize) * sessVars.GetCPUFactor()) / numTblWorkers
cost += sortCPUCost
}
return
}
// GetPlanCost calculates the cost of the plan if it has not been calculated yet and returns the cost.
func (p *PhysicalIndexLookUpReader) GetPlanCost(_ property.TaskType, option *PlanCostOption) (float64, error) {
costFlag := option.CostFlag
if p.planCostInit && !hasCostFlag(costFlag, CostFlagRecalculate) {
return p.planCost, nil
}
p.planCost = 0
// child's cost
for _, child := range []PhysicalPlan{p.indexPlan, p.tablePlan} {
childCost, err := child.GetPlanCost(property.CopDoubleReadTaskType, option)
if err != nil {
return 0, err
}
p.planCost += childCost
}
// to keep compatible with the previous cost implementation, re-calculate table-scan cost by using index stats-count again (see copTask.finishIndexPlan).
// TODO: amend table-side cost here later
var tmp PhysicalPlan
for tmp = p.tablePlan; len(tmp.Children()) > 0; tmp = tmp.Children()[0] {
}
ts := tmp.(*PhysicalTableScan)
if p.ctx.GetSessionVars().CostModelVersion == modelVer1 {
tblCost, err := ts.GetPlanCost(property.CopDoubleReadTaskType, option)
if err != nil {
return 0, err
}
p.planCost -= tblCost
p.planCost += getCardinality(p.indexPlan, costFlag) * ts.getScanRowSize() * p.SCtx().GetSessionVars().GetScanFactor(ts.Table)
}
// index-side net I/O cost: rows * row-size * net-factor
netFactor := getTableNetFactor(p.tablePlan)
rowSize := getTblStats(p.indexPlan).GetAvgRowSize(p.ctx, p.indexPlan.Schema().Columns, true, false)
p.planCost += getCardinality(p.indexPlan, costFlag) * rowSize * netFactor
// index-side net seek cost
p.planCost += estimateNetSeekCost(p.indexPlan)
// table-side net I/O cost: rows * row-size * net-factor
tblRowSize := getTblStats(p.tablePlan).GetAvgRowSize(p.ctx, p.tablePlan.Schema().Columns, false, false)
p.planCost += getCardinality(p.tablePlan, costFlag) * tblRowSize * netFactor
// table-side seek cost
p.planCost += estimateNetSeekCost(p.tablePlan)
// double read cost
p.planCost += p.estDoubleReadCost(ts.Table, costFlag)
// consider concurrency
p.planCost /= float64(p.ctx.GetSessionVars().DistSQLScanConcurrency())
// lookup-cpu-cost in TiDB
p.planCost += p.GetCost(costFlag)
p.planCostInit = true
return p.planCost, nil
}
func (p *PhysicalIndexLookUpReader) estDoubleReadCost(tbl *model.TableInfo, costFlag uint64) float64 {
if p.ctx.GetSessionVars().CostModelVersion == modelVer1 {
// only consider double-read cost on modelVer2
return 0
}
// estimate the double-read cost: (numDoubleReadTasks * seekFactor) / concurrency
doubleReadRows := getCardinality(p.indexPlan, costFlag)
batchSize := float64(p.ctx.GetSessionVars().IndexLookupSize)
concurrency := math.Max(1.0, float64(p.ctx.GetSessionVars().IndexLookupConcurrency()))
seekFactor := p.ctx.GetSessionVars().GetSeekFactor(tbl)
// distRatio indicates how many requests corresponding to a batch, current value is from experiments.
// TODO: estimate it by using index correlation or make it configurable.
distRatio := 40.0
numDoubleReadTasks := (doubleReadRows / batchSize) * distRatio // use Float64 instead of Int like `Ceil(...)` to make the cost continuous.
return (numDoubleReadTasks * seekFactor) / concurrency
}
// GetPlanCost calculates the cost of the plan if it has not been calculated yet and returns the cost.
func (p *PhysicalIndexReader) GetPlanCost(_ property.TaskType, option *PlanCostOption) (float64, error) {
costFlag := option.CostFlag
if p.planCostInit && !hasCostFlag(costFlag, CostFlagRecalculate) {
return p.planCost, nil
}
var rowCount, rowSize, netFactor, indexPlanCost, netSeekCost float64
sqlScanConcurrency := p.ctx.GetSessionVars().DistSQLScanConcurrency()
// child's cost
childCost, err := p.indexPlan.GetPlanCost(property.CopSingleReadTaskType, option)
if err != nil {
return 0, err
}
indexPlanCost = childCost
p.planCost = indexPlanCost
// net I/O cost: rows * row-size * net-factor
tblStats := getTblStats(p.indexPlan)
rowSize = tblStats.GetAvgRowSize(p.ctx, p.indexPlan.Schema().Columns, true, false)
rowCount = getCardinality(p.indexPlan, costFlag)
netFactor = getTableNetFactor(p.indexPlan)
p.planCost += rowCount * rowSize * netFactor
// net seek cost
netSeekCost = estimateNetSeekCost(p.indexPlan)
p.planCost += netSeekCost
// consider concurrency
p.planCost /= float64(sqlScanConcurrency)
if option.tracer != nil {
setPhysicalIndexReaderCostDetail(p, option.tracer, rowCount, rowSize, netFactor, netSeekCost, indexPlanCost, sqlScanConcurrency)
}
p.planCostInit = true
return p.planCost, nil
}
// GetNetDataSize calculates the cost of the plan in network data transfer.
func (p *PhysicalIndexReader) GetNetDataSize() float64 {
tblStats := getTblStats(p.indexPlan)
rowSize := tblStats.GetAvgRowSize(p.ctx, p.indexPlan.Schema().Columns, true, false)
return p.indexPlan.StatsCount() * rowSize
}
// GetPlanCost calculates the cost of the plan if it has not been calculated yet and returns the cost.
func (p *PhysicalTableReader) GetPlanCost(_ property.TaskType, option *PlanCostOption) (float64, error) {
costFlag := option.CostFlag
if p.planCostInit && !hasCostFlag(costFlag, CostFlagRecalculate) {
return p.planCost, nil
}
p.planCost = 0
netFactor := getTableNetFactor(p.tablePlan)
var rowCount, rowSize, netSeekCost, tableCost float64
sqlScanConcurrency := p.ctx.GetSessionVars().DistSQLScanConcurrency()
storeType := p.StoreType
switch storeType {
case kv.TiKV:
// child's cost
childCost, err := p.tablePlan.GetPlanCost(property.CopSingleReadTaskType, option)
if err != nil {
return 0, err
}
tableCost = childCost
p.planCost = childCost
// net I/O cost: rows * row-size * net-factor
rowSize = getTblStats(p.tablePlan).GetAvgRowSize(p.ctx, p.tablePlan.Schema().Columns, false, false)
rowCount = getCardinality(p.tablePlan, costFlag)
p.planCost += rowCount * rowSize * netFactor
// net seek cost
netSeekCost = estimateNetSeekCost(p.tablePlan)
p.planCost += netSeekCost
// consider concurrency
p.planCost /= float64(sqlScanConcurrency)
case kv.TiFlash:
var concurrency, rowSize, seekCost float64
_, isMPP := p.tablePlan.(*PhysicalExchangeSender)
if isMPP {
// mpp protocol
concurrency = p.ctx.GetSessionVars().CopTiFlashConcurrencyFactor
rowSize = collectRowSizeFromMPPPlan(p.tablePlan)
seekCost = accumulateNetSeekCost4MPP(p.tablePlan)
childCost, err := p.tablePlan.GetPlanCost(property.MppTaskType, option)
if err != nil {
return 0, err
}
p.planCost = childCost
} else {
// cop protocol
concurrency = float64(p.ctx.GetSessionVars().DistSQLScanConcurrency())
rowSize = getTblStats(p.tablePlan).GetAvgRowSize(p.ctx, p.tablePlan.Schema().Columns, false, false)
seekCost = estimateNetSeekCost(p.tablePlan)
tType := property.MppTaskType
if p.ctx.GetSessionVars().CostModelVersion == modelVer1 {
// regard the underlying tasks as cop-task on modelVer1 for compatibility
tType = property.CopSingleReadTaskType
}
childCost, err := p.tablePlan.GetPlanCost(tType, option)
if err != nil {
return 0, err
}
p.planCost = childCost
}
// net I/O cost
p.planCost += getCardinality(p.tablePlan, costFlag) * rowSize * netFactor
// net seek cost
p.planCost += seekCost
// consider concurrency
p.planCost /= concurrency
// consider tidb_enforce_mpp
if isMPP && p.ctx.GetSessionVars().IsMPPEnforced() &&
!hasCostFlag(costFlag, CostFlagRecalculate) { // show the real cost in explain-statements
p.planCost /= 1000000000
}
}
if option.tracer != nil {
setPhysicalTableReaderCostDetail(p, option.tracer,
rowCount, rowSize, netFactor, netSeekCost, tableCost,
sqlScanConcurrency, storeType)
}
p.planCostInit = true
return p.planCost, nil
}
// GetNetDataSize calculates the estimated total data size fetched from storage.
func (p *PhysicalTableReader) GetNetDataSize() float64 {
rowSize := getTblStats(p.tablePlan).GetAvgRowSize(p.ctx, p.tablePlan.Schema().Columns, false, false)
return p.tablePlan.StatsCount() * rowSize
}
// GetPlanCost calculates the cost of the plan if it has not been calculated yet and returns the cost.
func (p *PhysicalIndexMergeReader) GetPlanCost(_ property.TaskType, option *PlanCostOption) (float64, error) {
costFlag := option.CostFlag
if p.planCostInit && !hasCostFlag(costFlag, CostFlagRecalculate) {
return p.planCost, nil
}
p.planCost = 0
if tblScan := p.tablePlan; tblScan != nil {
childCost, err := tblScan.GetPlanCost(property.CopSingleReadTaskType, option)
if err != nil {
return 0, err
}
netFactor := getTableNetFactor(tblScan)
p.planCost += childCost // child's cost
tblStats := getTblStats(tblScan)
rowSize := tblStats.GetAvgRowSize(p.ctx, tblScan.Schema().Columns, false, false)
p.planCost += getCardinality(tblScan, costFlag) * rowSize * netFactor // net I/O cost
}
for _, partialScan := range p.partialPlans {
childCost, err := partialScan.GetPlanCost(property.CopSingleReadTaskType, option)
if err != nil {
return 0, err
}
var isIdxScan bool
for p := partialScan; ; p = p.Children()[0] {
_, isIdxScan = p.(*PhysicalIndexScan)
if len(p.Children()) == 0 {
break
}
}
netFactor := getTableNetFactor(partialScan)
p.planCost += childCost // child's cost
tblStats := getTblStats(partialScan)
rowSize := tblStats.GetAvgRowSize(p.ctx, partialScan.Schema().Columns, isIdxScan, false)
p.planCost += getCardinality(partialScan, costFlag) * rowSize * netFactor // net I/O cost
}
// TODO: accumulate table-side seek cost
// consider concurrency
copIterWorkers := float64(p.ctx.GetSessionVars().DistSQLScanConcurrency())
p.planCost /= copIterWorkers
p.planCostInit = true
return p.planCost, nil
}
// GetPartialReaderNetDataSize returns the estimated total response data size of a partial read.
func (p *PhysicalIndexMergeReader) GetPartialReaderNetDataSize(plan PhysicalPlan) float64 {
_, isIdxScan := plan.(*PhysicalIndexScan)
return plan.StatsCount() * getTblStats(plan).GetAvgRowSize(p.ctx, plan.Schema().Columns, isIdxScan, false)
}
// GetPlanCost calculates the cost of the plan if it has not been calculated yet and returns the cost.
func (p *PhysicalTableScan) GetPlanCost(taskType property.TaskType, option *PlanCostOption) (float64, error) {
costFlag := option.CostFlag
if p.planCostInit && !hasCostFlag(costFlag, CostFlagRecalculate) {
return p.planCost, nil
}
var selfCost float64
var rowCount, rowSize, scanFactor float64
costModelVersion := p.ctx.GetSessionVars().CostModelVersion
switch costModelVersion {
case modelVer1: // scan cost: rows * row-size * scan-factor
scanFactor = p.ctx.GetSessionVars().GetScanFactor(p.Table)
if p.Desc && p.prop != nil && p.prop.ExpectedCnt >= smallScanThreshold {
scanFactor = p.ctx.GetSessionVars().GetDescScanFactor(p.Table)
}
rowCount = getCardinality(p, costFlag)
rowSize = p.getScanRowSize()
selfCost = rowCount * rowSize * scanFactor
case modelVer2: // scan cost: rows * log2(row-size) * scan-factor
switch taskType {
case property.MppTaskType: // use a dedicated scan-factor for TiFlash
// no need to distinguish `Scan` and `DescScan` for TiFlash for now
scanFactor = p.ctx.GetSessionVars().GetTiFlashScanFactor()
default: // for TiKV
scanFactor = p.ctx.GetSessionVars().GetScanFactor(p.Table)
if p.Desc {
scanFactor = p.ctx.GetSessionVars().GetDescScanFactor(p.Table)
}
}
// the formula `log(rowSize)` is based on experiment results
rowSize = math.Max(p.getScanRowSize(), 2.0) // to guarantee logRowSize >= 1
logRowSize := math.Log2(rowSize)
rowCount = getCardinality(p, costFlag)
selfCost = rowCount * logRowSize * scanFactor
// give TiFlash a start-up cost to let the optimizer prefers to use TiKV to process small table scans.
if p.StoreType == kv.TiFlash {
selfCost += 2000 * logRowSize * scanFactor
}
}
if option.tracer != nil {
setPhysicalTableOrIndexScanCostDetail(p, option.tracer, rowCount, rowSize, scanFactor, costModelVersion)
}
p.planCost = selfCost
p.planCostInit = true
return p.planCost, nil
}
// GetPlanCost calculates the cost of the plan if it has not been calculated yet and returns the cost.
func (p *PhysicalIndexScan) GetPlanCost(_ property.TaskType, option *PlanCostOption) (float64, error) {
costFlag := option.CostFlag
if p.planCostInit && !hasCostFlag(costFlag, CostFlagRecalculate) {
return p.planCost, nil
}
var selfCost float64
var rowCount, rowSize, scanFactor float64
costModelVersion := p.ctx.GetSessionVars().CostModelVersion
switch costModelVersion {
case modelVer1: // scan cost: rows * row-size * scan-factor
scanFactor = p.ctx.GetSessionVars().GetScanFactor(p.Table)
if p.Desc && p.prop != nil && p.prop.ExpectedCnt >= smallScanThreshold {
scanFactor = p.ctx.GetSessionVars().GetDescScanFactor(p.Table)
}
rowCount = getCardinality(p, costFlag)
rowSize = p.getScanRowSize()
selfCost = rowCount * rowSize * scanFactor
case modelVer2:
scanFactor = p.ctx.GetSessionVars().GetScanFactor(p.Table)
if p.Desc {
scanFactor = p.ctx.GetSessionVars().GetDescScanFactor(p.Table)
}
rowCount = getCardinality(p, costFlag)
rowSize = math.Max(p.getScanRowSize(), 2.0)
logRowSize := math.Log2(rowSize)
selfCost = rowCount * logRowSize * scanFactor
}
if option.tracer != nil {
setPhysicalTableOrIndexScanCostDetail(p, option.tracer, rowCount, rowSize, scanFactor, costModelVersion)
}
p.planCost = selfCost
p.planCostInit = true
return p.planCost, nil
}
// GetCost computes the cost of index join operator and its children.
func (p *PhysicalIndexJoin) GetCost(outerCnt, innerCnt, outerCost, innerCost float64, costFlag uint64) float64 {
var cpuCost float64
sessVars := p.ctx.GetSessionVars()
// Add the cost of evaluating outer filter, since inner filter of index join
// is always empty, we can simply tell whether outer filter is empty using the
// summed length of left/right conditions.
if len(p.LeftConditions)+len(p.RightConditions) > 0 {
cpuCost += sessVars.GetCPUFactor() * outerCnt
outerCnt *= SelectionFactor
}
// Cost of extracting lookup keys.
innerCPUCost := sessVars.GetCPUFactor() * outerCnt
// Cost of sorting and removing duplicate lookup keys:
// (outerCnt / batchSize) * (batchSize * Log2(batchSize) + batchSize) * CPUFactor
batchSize := math.Min(float64(p.ctx.GetSessionVars().IndexJoinBatchSize), outerCnt)
if batchSize > 2 {
innerCPUCost += outerCnt * (math.Log2(batchSize) + 1) * sessVars.GetCPUFactor()
}
// Add cost of building inner executors. CPU cost of building copTasks:
// (outerCnt / batchSize) * (batchSize * distinctFactor) * CPUFactor
// Since we don't know the number of copTasks built, ignore these network cost now.
innerCPUCost += outerCnt * distinctFactor * sessVars.GetCPUFactor()
// CPU cost of building hash table for inner results:
// (outerCnt / batchSize) * (batchSize * distinctFactor) * innerCnt * CPUFactor
innerCPUCost += outerCnt * distinctFactor * innerCnt * sessVars.GetCPUFactor()
innerConcurrency := float64(p.ctx.GetSessionVars().IndexLookupJoinConcurrency())
cpuCost += innerCPUCost / innerConcurrency
// Cost of probing hash table in main thread.
numPairs := outerCnt * innerCnt
if p.JoinType == SemiJoin || p.JoinType == AntiSemiJoin ||
p.JoinType == LeftOuterSemiJoin || p.JoinType == AntiLeftOuterSemiJoin {
if len(p.OtherConditions) > 0 {
numPairs *= 0.5
} else {
numPairs = 0
}
}
if hasCostFlag(costFlag, CostFlagUseTrueCardinality) {
numPairs = getOperatorActRows(p)
}
probeCost := numPairs * sessVars.GetCPUFactor()
// Cost of additional concurrent goroutines.
cpuCost += probeCost + (innerConcurrency+1.0)*sessVars.GetConcurrencyFactor()
// Memory cost of hash tables for inner rows. The computed result is the upper bound,
// since the executor is pipelined and not all workers are always in full load.
memoryCost := innerConcurrency * (batchSize * distinctFactor) * innerCnt * sessVars.GetMemoryFactor()
// Cost of inner child plan, i.e, mainly I/O and network cost.
innerPlanCost := outerCnt * innerCost
if p.ctx.GetSessionVars().CostModelVersion == 2 {
// IndexJoin executes a batch of rows at a time, so the actual cost of this part should be
// `innerCostPerBatch * numberOfBatches` instead of `innerCostPerRow * numberOfOuterRow`.
// Use an empirical value batchRatio to handle this now.
// TODO: remove this empirical value.
batchRatio := 30.0
innerPlanCost /= batchRatio
}
return outerCost + innerPlanCost + cpuCost + memoryCost + p.estDoubleReadCost(outerCnt)
}
func (p *PhysicalIndexJoin) estDoubleReadCost(doubleReadRows float64) float64 {
if p.ctx.GetSessionVars().CostModelVersion == modelVer1 {
// only consider double-read cost on modelVer2
return 0
}
// estimate the double read cost for IndexJoin: (double-read-tasks * seek-factor) / concurrency
seekFactor := p.ctx.GetSessionVars().GetSeekFactor(nil)
batchSize := math.Max(1.0, float64(p.ctx.GetSessionVars().IndexJoinBatchSize))
concurrency := math.Max(1.0, float64(p.ctx.GetSessionVars().IndexLookupJoinConcurrency()))
// distRatio indicates how many requests corresponding to a batch, current value is from experiments.
// TODO: estimate it by using index correlation or make it configurable.
distRatio := 40.0
numDoubleReadTasks := (doubleReadRows / batchSize) * distRatio
return (numDoubleReadTasks * seekFactor) / concurrency
}
// GetPlanCost calculates the cost of the plan if it has not been calculated yet and returns the cost.
func (p *PhysicalIndexJoin) GetPlanCost(taskType property.TaskType, option *PlanCostOption) (float64, error) {
costFlag := option.CostFlag
if p.planCostInit && !hasCostFlag(costFlag, CostFlagRecalculate) {
return p.planCost, nil
}
outerChild, innerChild := p.children[1-p.InnerChildIdx], p.children[p.InnerChildIdx]
outerCost, err := outerChild.GetPlanCost(taskType, option)
if err != nil {
return 0, err
}
innerCost, err := innerChild.GetPlanCost(taskType, option)
if err != nil {
return 0, err
}
outerCnt := getCardinality(outerChild, costFlag)
innerCnt := getCardinality(innerChild, costFlag)
if hasCostFlag(costFlag, CostFlagUseTrueCardinality) && outerCnt > 0 {
innerCnt /= outerCnt // corresponding to one outer row when calculating IndexJoin costs
innerCost /= outerCnt
}
p.planCost = p.GetCost(outerCnt, innerCnt, outerCost, innerCost, costFlag)
p.planCostInit = true
return p.planCost, nil
}
// GetCost computes the cost of index merge join operator and its children.
func (p *PhysicalIndexHashJoin) GetCost(outerCnt, innerCnt, outerCost, innerCost float64, costFlag uint64) float64 {
var cpuCost float64
sessVars := p.ctx.GetSessionVars()
// Add the cost of evaluating outer filter, since inner filter of index join
// is always empty, we can simply tell whether outer filter is empty using the
// summed length of left/right conditions.
if len(p.LeftConditions)+len(p.RightConditions) > 0 {
cpuCost += sessVars.GetCPUFactor() * outerCnt
outerCnt *= SelectionFactor
}
// Cost of extracting lookup keys.
innerCPUCost := sessVars.GetCPUFactor() * outerCnt
// Cost of sorting and removing duplicate lookup keys:
// (outerCnt / batchSize) * (batchSize * Log2(batchSize) + batchSize) * CPUFactor
batchSize := math.Min(float64(sessVars.IndexJoinBatchSize), outerCnt)
if batchSize > 2 {
innerCPUCost += outerCnt * (math.Log2(batchSize) + 1) * sessVars.GetCPUFactor()
}
// Add cost of building inner executors. CPU cost of building copTasks:
// (outerCnt / batchSize) * (batchSize * distinctFactor) * CPUFactor
// Since we don't know the number of copTasks built, ignore these network cost now.
innerCPUCost += outerCnt * distinctFactor * sessVars.GetCPUFactor()
concurrency := float64(sessVars.IndexLookupJoinConcurrency())
cpuCost += innerCPUCost / concurrency
// CPU cost of building hash table for outer results concurrently.
// (outerCnt / batchSize) * (batchSize * CPUFactor)
outerCPUCost := outerCnt * sessVars.GetCPUFactor()
cpuCost += outerCPUCost / concurrency
// Cost of probing hash table concurrently.
numPairs := outerCnt * innerCnt
if p.JoinType == SemiJoin || p.JoinType == AntiSemiJoin ||
p.JoinType == LeftOuterSemiJoin || p.JoinType == AntiLeftOuterSemiJoin {
if len(p.OtherConditions) > 0 {
numPairs *= 0.5
} else {
numPairs = 0
}
}
if hasCostFlag(costFlag, CostFlagUseTrueCardinality) {
numPairs = getOperatorActRows(p)
}
// Inner workers do hash join in parallel, but they can only save ONE outer
// batch results. So as the number of outer batch exceeds inner concurrency,
// it would fall back to linear execution. In a word, the hash join only runs
// in parallel for the first `innerConcurrency` number of inner tasks.
var probeCost float64
if outerCnt/batchSize >= concurrency {
probeCost = (numPairs - batchSize*innerCnt*(concurrency-1)) * sessVars.GetCPUFactor()
} else {
probeCost = batchSize * innerCnt * sessVars.GetCPUFactor()
}
cpuCost += probeCost
// Cost of additional concurrent goroutines.
cpuCost += (concurrency + 1.0) * sessVars.GetConcurrencyFactor()
// Memory cost of hash tables for outer rows. The computed result is the upper bound,
// since the executor is pipelined and not all workers are always in full load.
memoryCost := concurrency * (batchSize * distinctFactor) * innerCnt * sessVars.GetMemoryFactor()
// Cost of inner child plan, i.e, mainly I/O and network cost.
innerPlanCost := outerCnt * innerCost
return outerCost + innerPlanCost + cpuCost + memoryCost + p.estDoubleReadCost(outerCnt)
}
// GetPlanCost calculates the cost of the plan if it has not been calculated yet and returns the cost.
func (p *PhysicalIndexHashJoin) GetPlanCost(taskType property.TaskType, option *PlanCostOption) (float64, error) {
costFlag := option.CostFlag
if p.planCostInit && !hasCostFlag(costFlag, CostFlagRecalculate) {
return p.planCost, nil
}
outerChild, innerChild := p.children[1-p.InnerChildIdx], p.children[p.InnerChildIdx]
outerCost, err := outerChild.GetPlanCost(taskType, option)
if err != nil {
return 0, err
}
innerCost, err := innerChild.GetPlanCost(taskType, option)
if err != nil {
return 0, err
}
outerCnt := getCardinality(outerChild, costFlag)
innerCnt := getCardinality(innerChild, costFlag)
if hasCostFlag(costFlag, CostFlagUseTrueCardinality) && outerCnt > 0 {
innerCnt /= outerCnt // corresponding to one outer row when calculating IndexJoin costs
innerCost /= outerCnt
}
p.planCost = p.GetCost(outerCnt, innerCnt, outerCost, innerCost, costFlag)
p.planCostInit = true
return p.planCost, nil
}
// GetCost computes the cost of index merge join operator and its children.
func (p *PhysicalIndexMergeJoin) GetCost(outerCnt, innerCnt, outerCost, innerCost float64, costFlag uint64) float64 {
var cpuCost float64
sessVars := p.ctx.GetSessionVars()
// Add the cost of evaluating outer filter, since inner filter of index join
// is always empty, we can simply tell whether outer filter is empty using the
// summed length of left/right conditions.
if len(p.LeftConditions)+len(p.RightConditions) > 0 {
cpuCost += sessVars.GetCPUFactor() * outerCnt
outerCnt *= SelectionFactor
}
// Cost of extracting lookup keys.
innerCPUCost := sessVars.GetCPUFactor() * outerCnt
// Cost of sorting and removing duplicate lookup keys:
// (outerCnt / batchSize) * (sortFactor + 1.0) * batchSize * cpuFactor
// If `p.NeedOuterSort` is true, the sortFactor is batchSize * Log2(batchSize).
// Otherwise, it's 0.
batchSize := math.Min(float64(p.ctx.GetSessionVars().IndexJoinBatchSize), outerCnt)
sortFactor := 0.0
if p.NeedOuterSort {
sortFactor = math.Log2(batchSize)
}
if batchSize > 2 {
innerCPUCost += outerCnt * (sortFactor + 1.0) * sessVars.GetCPUFactor()
}
// Add cost of building inner executors. CPU cost of building copTasks:
// (outerCnt / batchSize) * (batchSize * distinctFactor) * cpuFactor
// Since we don't know the number of copTasks built, ignore these network cost now.
innerCPUCost += outerCnt * distinctFactor * sessVars.GetCPUFactor()
innerConcurrency := float64(p.ctx.GetSessionVars().IndexLookupJoinConcurrency())
cpuCost += innerCPUCost / innerConcurrency
// Cost of merge join in inner worker.
numPairs := outerCnt * innerCnt
if p.JoinType == SemiJoin || p.JoinType == AntiSemiJoin ||
p.JoinType == LeftOuterSemiJoin || p.JoinType == AntiLeftOuterSemiJoin {
if len(p.OtherConditions) > 0 {
numPairs *= 0.5
} else {
numPairs = 0
}
}
if hasCostFlag(costFlag, CostFlagUseTrueCardinality) {
numPairs = getOperatorActRows(p)
}
avgProbeCnt := numPairs / outerCnt
var probeCost float64
// Inner workers do merge join in parallel, but they can only save ONE outer batch
// results. So as the number of outer batch exceeds inner concurrency, it would fall back to
// linear execution. In a word, the merge join only run in parallel for the first
// `innerConcurrency` number of inner tasks.
if outerCnt/batchSize >= innerConcurrency {
probeCost = (numPairs - batchSize*avgProbeCnt*(innerConcurrency-1)) * sessVars.GetCPUFactor()
} else {
probeCost = batchSize * avgProbeCnt * sessVars.GetCPUFactor()
}
cpuCost += probeCost + (innerConcurrency+1.0)*sessVars.GetConcurrencyFactor()
// Index merge join save the join results in inner worker.
// So the memory cost consider the results size for each batch.
memoryCost := innerConcurrency * (batchSize * avgProbeCnt) * sessVars.GetMemoryFactor()
innerPlanCost := outerCnt * innerCost
return outerCost + innerPlanCost + cpuCost + memoryCost + p.estDoubleReadCost(outerCnt)
}
// GetPlanCost calculates the cost of the plan if it has not been calculated yet and returns the cost.
func (p *PhysicalIndexMergeJoin) GetPlanCost(taskType property.TaskType, option *PlanCostOption) (float64, error) {
costFlag := option.CostFlag
if p.planCostInit && !hasCostFlag(costFlag, CostFlagRecalculate) {
return p.planCost, nil
}
outerChild, innerChild := p.children[1-p.InnerChildIdx], p.children[p.InnerChildIdx]
outerCost, err := outerChild.GetPlanCost(taskType, option)
if err != nil {
return 0, err
}
innerCost, err := innerChild.GetPlanCost(taskType, option)
if err != nil {
return 0, err
}
outerCnt := getCardinality(outerChild, costFlag)
innerCnt := getCardinality(innerChild, costFlag)
if hasCostFlag(costFlag, CostFlagUseTrueCardinality) && outerCnt > 0 {
innerCnt /= outerCnt // corresponding to one outer row when calculating IndexJoin costs
innerCost /= outerCnt
}
p.planCost = p.GetCost(outerCnt, innerCnt, outerCost, innerCost, costFlag)
p.planCostInit = true
return p.planCost, nil
}
// GetCost computes the cost of apply operator.
func (p *PhysicalApply) GetCost(lCount, rCount, lCost, rCost float64) float64 {
var cpuCost float64
sessVars := p.ctx.GetSessionVars()
if len(p.LeftConditions) > 0 {
cpuCost += lCount * sessVars.GetCPUFactor()
lCount *= SelectionFactor
}
if len(p.RightConditions) > 0 {
cpuCost += lCount * rCount * sessVars.GetCPUFactor()
rCount *= SelectionFactor
}
if len(p.EqualConditions)+len(p.OtherConditions) > 0 {
if p.JoinType == SemiJoin || p.JoinType == AntiSemiJoin ||
p.JoinType == LeftOuterSemiJoin || p.JoinType == AntiLeftOuterSemiJoin {
cpuCost += lCount * rCount * sessVars.GetCPUFactor() * 0.5
} else {
cpuCost += lCount * rCount * sessVars.GetCPUFactor()
}
}
// Apply uses a NestedLoop method for execution.
// For every row from the left(outer) side, it executes
// the whole right(inner) plan tree. So the cost of apply
// should be : apply cost + left cost + left count * right cost
return cpuCost + lCost + lCount*rCost
}
// GetPlanCost calculates the cost of the plan if it has not been calculated yet and returns the cost.
func (p *PhysicalApply) GetPlanCost(taskType property.TaskType, option *PlanCostOption) (float64, error) {
costFlag := option.CostFlag
if p.planCostInit && !hasCostFlag(costFlag, CostFlagRecalculate) {
return p.planCost, nil
}
outerChild, innerChild := p.children[1-p.InnerChildIdx], p.children[p.InnerChildIdx]
outerCost, err := outerChild.GetPlanCost(taskType, option)
if err != nil {
return 0, err
}
innerCost, err := innerChild.GetPlanCost(taskType, option)
if err != nil {
return 0, err
}
outerCnt := getCardinality(outerChild, costFlag)
innerCnt := getCardinality(innerChild, costFlag)
p.planCost = p.GetCost(outerCnt, innerCnt, outerCost, innerCost)
p.planCostInit = true
return p.planCost, nil
}
// GetCost computes cost of merge join operator itself.
func (p *PhysicalMergeJoin) GetCost(lCnt, rCnt float64, costFlag uint64) float64 {
outerCnt := lCnt
innerCnt := rCnt
innerKeys := p.RightJoinKeys
innerSchema := p.children[1].Schema()
innerStats := p.children[1].statsInfo()
if p.JoinType == RightOuterJoin {
outerCnt = rCnt
innerCnt = lCnt
innerKeys = p.LeftJoinKeys
innerSchema = p.children[0].Schema()
innerStats = p.children[0].statsInfo()
}
helper := &fullJoinRowCountHelper{
sctx: p.SCtx(),
cartesian: false,
leftProfile: p.children[0].statsInfo(),
rightProfile: p.children[1].statsInfo(),
leftJoinKeys: p.LeftJoinKeys,
rightJoinKeys: p.RightJoinKeys,
leftSchema: p.children[0].Schema(),
rightSchema: p.children[1].Schema(),
}
numPairs := helper.estimate()
if p.JoinType == SemiJoin || p.JoinType == AntiSemiJoin ||
p.JoinType == LeftOuterSemiJoin || p.JoinType == AntiLeftOuterSemiJoin {
if len(p.OtherConditions) > 0 {
numPairs *= 0.5
} else {
numPairs = 0
}
}
if hasCostFlag(costFlag, CostFlagUseTrueCardinality) {
numPairs = getOperatorActRows(p)
}
sessVars := p.ctx.GetSessionVars()
probeCost := numPairs * sessVars.GetCPUFactor()
// Cost of evaluating outer filters.
var cpuCost float64
if len(p.LeftConditions)+len(p.RightConditions) > 0 {
probeCost *= SelectionFactor
cpuCost += outerCnt * sessVars.GetCPUFactor()
}
cpuCost += probeCost
// For merge join, only one group of rows with same join key(not null) are cached,
// we compute average memory cost using estimated group size.
NDV, _ := getColsNDVWithMatchedLen(innerKeys, innerSchema, innerStats)
memoryCost := (innerCnt / NDV) * sessVars.GetMemoryFactor()
return cpuCost + memoryCost
}
// GetPlanCost calculates the cost of the plan if it has not been calculated yet and returns the cost.
func (p *PhysicalMergeJoin) GetPlanCost(taskType property.TaskType, option *PlanCostOption) (float64, error) {
costFlag := option.CostFlag
if p.planCostInit && !hasCostFlag(costFlag, CostFlagRecalculate) {
return p.planCost, nil
}
p.planCost = 0
for _, child := range p.children {
childCost, err := child.GetPlanCost(taskType, option)
if err != nil {
return 0, err
}
p.planCost += childCost
}
p.planCost += p.GetCost(getCardinality(p.children[0], costFlag), getCardinality(p.children[1], costFlag), costFlag)
p.planCostInit = true
return p.planCost, nil
}
// GetCost computes cost of hash join operator itself.
func (p *PhysicalHashJoin) GetCost(lCnt, rCnt float64, isMPP bool, costFlag uint64, op *physicalOptimizeOp) float64 {
buildCnt, probeCnt := lCnt, rCnt
build := p.children[0]
// Taking the right as the inner for right join or using the outer to build a hash table.
if (p.InnerChildIdx == 1 && !p.UseOuterToBuild) || (p.InnerChildIdx == 0 && p.UseOuterToBuild) {
buildCnt, probeCnt = rCnt, lCnt
build = p.children[1]
}
sessVars := p.ctx.GetSessionVars()
oomUseTmpStorage := variable.EnableTmpStorageOnOOM.Load()
memQuota := sessVars.StmtCtx.MemTracker.GetBytesLimit() // sessVars.MemQuotaQuery && hint
rowSize := getAvgRowSize(build.statsInfo(), build.Schema())
spill := oomUseTmpStorage && memQuota > 0 && rowSize*buildCnt > float64(memQuota) && p.storeTp != kv.TiFlash
// Cost of building hash table.
cpuFactor := sessVars.GetCPUFactor()
if isMPP && p.ctx.GetSessionVars().CostModelVersion == modelVer2 {
cpuFactor = sessVars.GetTiFlashCPUFactor() // use the dedicated TiFlash CPU Factor on modelVer2
}
diskFactor := sessVars.GetDiskFactor()
memoryFactor := sessVars.GetMemoryFactor()
concurrencyFactor := sessVars.GetConcurrencyFactor()
cpuCost := buildCnt * cpuFactor
memoryCost := buildCnt * memoryFactor
diskCost := buildCnt * diskFactor * rowSize
// Number of matched row pairs regarding the equal join conditions.
helper := &fullJoinRowCountHelper{
sctx: p.SCtx(),
cartesian: false,
leftProfile: p.children[0].statsInfo(),
rightProfile: p.children[1].statsInfo(),
leftJoinKeys: p.LeftJoinKeys,
rightJoinKeys: p.RightJoinKeys,
leftSchema: p.children[0].Schema(),
rightSchema: p.children[1].Schema(),
}
numPairs := helper.estimate()
// For semi-join class, if `OtherConditions` is empty, we already know
// the join results after querying hash table, otherwise, we have to
// evaluate those resulted row pairs after querying hash table; if we
// find one pair satisfying the `OtherConditions`, we then know the
// join result for this given outer row, otherwise we have to iterate
// to the end of those pairs; since we have no idea about when we can
// terminate the iteration, we assume that we need to iterate half of
// those pairs in average.
if p.JoinType == SemiJoin || p.JoinType == AntiSemiJoin ||
p.JoinType == LeftOuterSemiJoin || p.JoinType == AntiLeftOuterSemiJoin {
if len(p.OtherConditions) > 0 {
numPairs *= 0.5
} else {
numPairs = 0
}
}
if hasCostFlag(costFlag, CostFlagUseTrueCardinality) {
numPairs = getOperatorActRows(p)
}
// Cost of querying hash table is cheap actually, so we just compute the cost of
// evaluating `OtherConditions` and joining row pairs.
probeCost := numPairs * cpuFactor
probeDiskCost := numPairs * diskFactor * rowSize
// Cost of evaluating outer filter.
if len(p.LeftConditions)+len(p.RightConditions) > 0 {
// Input outer count for the above compution should be adjusted by SelectionFactor.
probeCost *= SelectionFactor
probeDiskCost *= SelectionFactor
probeCost += probeCnt * cpuFactor
}
diskCost += probeDiskCost
probeCost /= float64(p.Concurrency)
// Cost of additional concurrent goroutines.
cpuCost += probeCost + float64(p.Concurrency+1)*concurrencyFactor
// Cost of traveling the hash table to resolve missing matched cases when building the hash table from the outer table
if p.UseOuterToBuild {
if spill {
// It runs in sequence when build data is on disk. See handleUnmatchedRowsFromHashTableInDisk
cpuCost += buildCnt * cpuFactor
} else {
cpuCost += buildCnt * cpuFactor / float64(p.Concurrency)
}
diskCost += buildCnt * diskFactor * rowSize
}
if spill {
memoryCost *= float64(memQuota) / (rowSize * buildCnt)
} else {
diskCost = 0
}
if op != nil {
setPhysicalHashJoinCostDetail(p, op, spill, buildCnt, probeCnt, cpuFactor, rowSize, numPairs,
cpuCost, probeCost, memoryCost, diskCost, probeDiskCost,
diskFactor, memoryFactor, concurrencyFactor,
memQuota)
}
return cpuCost + memoryCost + diskCost
}
// GetPlanCost calculates the cost of the plan if it has not been calculated yet and returns the cost.
func (p *PhysicalHashJoin) GetPlanCost(taskType property.TaskType, option *PlanCostOption) (float64, error) {
costFlag := option.CostFlag
if p.planCostInit && !hasCostFlag(costFlag, CostFlagRecalculate) {
return p.planCost, nil
}
p.planCost = 0
for _, child := range p.children {
childCost, err := child.GetPlanCost(taskType, option)
if err != nil {
return 0, err
}
p.planCost += childCost
}
p.planCost += p.GetCost(getCardinality(p.children[0], costFlag), getCardinality(p.children[1], costFlag),
taskType == property.MppTaskType, costFlag, option.tracer)
p.planCostInit = true
return p.planCost, nil
}
// GetCost computes cost of stream aggregation considering CPU/memory.
func (p *PhysicalStreamAgg) GetCost(inputRows float64, isRoot, isMPP bool, costFlag uint64) float64 {
aggFuncFactor := p.getAggFuncCostFactor(false)
var cpuCost float64
sessVars := p.ctx.GetSessionVars()
if isRoot {
cpuCost = inputRows * sessVars.GetCPUFactor() * aggFuncFactor
} else if isMPP {
if p.ctx.GetSessionVars().CostModelVersion == modelVer2 {
// use the dedicated CPU factor for TiFlash on modelVer2
cpuCost = inputRows * sessVars.GetTiFlashCPUFactor() * aggFuncFactor
} else {
cpuCost = inputRows * sessVars.GetCopCPUFactor() * aggFuncFactor
}
} else {
cpuCost = inputRows * sessVars.GetCopCPUFactor() * aggFuncFactor
}
rowsPerGroup := inputRows / getCardinality(p, costFlag)
memoryCost := rowsPerGroup * distinctFactor * sessVars.GetMemoryFactor() * float64(p.numDistinctFunc())
return cpuCost + memoryCost
}
// GetPlanCost calculates the cost of the plan if it has not been calculated yet and returns the cost.
func (p *PhysicalStreamAgg) GetPlanCost(taskType property.TaskType, option *PlanCostOption) (float64, error) {
costFlag := option.CostFlag
if p.planCostInit && !hasCostFlag(costFlag, CostFlagRecalculate) {
return p.planCost, nil
}
childCost, err := p.children[0].GetPlanCost(taskType, option)
if err != nil {
return 0, err
}
p.planCost = childCost
p.planCost += p.GetCost(getCardinality(p.children[0], costFlag), taskType == property.RootTaskType, taskType == property.MppTaskType, costFlag)
p.planCostInit = true
return p.planCost, nil
}
// GetCost computes the cost of hash aggregation considering CPU/memory.
func (p *PhysicalHashAgg) GetCost(inputRows float64, isRoot, isMPP bool, costFlag uint64) float64 {
cardinality := getCardinality(p, costFlag)
numDistinctFunc := p.numDistinctFunc()
aggFuncFactor := p.getAggFuncCostFactor(isMPP)
var cpuCost float64
sessVars := p.ctx.GetSessionVars()
if isRoot {
cpuCost = inputRows * sessVars.GetCPUFactor() * aggFuncFactor
divisor, con := p.cpuCostDivisor(numDistinctFunc > 0)
if divisor > 0 {
cpuCost /= divisor
// Cost of additional goroutines.
cpuCost += (con + 1) * sessVars.GetConcurrencyFactor()
}
} else if isMPP {
if p.ctx.GetSessionVars().CostModelVersion == modelVer2 {
// use the dedicated CPU factor for TiFlash on modelVer2
cpuCost = inputRows * sessVars.GetTiFlashCPUFactor() * aggFuncFactor
} else {
cpuCost = inputRows * sessVars.GetCopCPUFactor() * aggFuncFactor
}
} else {
cpuCost = inputRows * sessVars.GetCopCPUFactor() * aggFuncFactor
}
memoryCost := cardinality * sessVars.GetMemoryFactor() * float64(len(p.AggFuncs))
// When aggregation has distinct flag, we would allocate a map for each group to
// check duplication.
memoryCost += inputRows * distinctFactor * sessVars.GetMemoryFactor() * float64(numDistinctFunc)
return cpuCost + memoryCost
}
// GetPlanCost calculates the cost of the plan if it has not been calculated yet and returns the cost.
func (p *PhysicalHashAgg) GetPlanCost(taskType property.TaskType, option *PlanCostOption) (float64, error) {
costFlag := option.CostFlag
if p.planCostInit && !hasCostFlag(costFlag, CostFlagRecalculate) {
return p.planCost, nil
}
childCost, err := p.children[0].GetPlanCost(taskType, option)
if err != nil {
return 0, err
}
p.planCost = childCost
statsCnt := getCardinality(p.children[0], costFlag)
switch taskType {
case property.RootTaskType:
p.planCost += p.GetCost(statsCnt, true, false, costFlag)
case property.CopSingleReadTaskType, property.CopDoubleReadTaskType:
p.planCost += p.GetCost(statsCnt, false, false, costFlag)
case property.MppTaskType:
p.planCost += p.GetCost(statsCnt, false, true, costFlag)
default:
return 0, errors.Errorf("unknown task type %v", taskType)
}
p.planCostInit = true
return p.planCost, nil
}
// GetCost computes the cost of in memory sort.
func (p *PhysicalSort) GetCost(count float64, schema *expression.Schema) float64 {
if count < 2.0 {
count = 2.0
}
sessVars := p.ctx.GetSessionVars()
cpuCost := count * math.Log2(count) * sessVars.GetCPUFactor()
memoryCost := count * sessVars.GetMemoryFactor()
oomUseTmpStorage := variable.EnableTmpStorageOnOOM.Load()
memQuota := sessVars.StmtCtx.MemTracker.GetBytesLimit() // sessVars.MemQuotaQuery && hint
rowSize := getAvgRowSize(p.statsInfo(), schema)
spill := oomUseTmpStorage && memQuota > 0 && rowSize*count > float64(memQuota)
diskCost := count * sessVars.GetDiskFactor() * rowSize
if !spill {
diskCost = 0
} else {
memoryCost *= float64(memQuota) / (rowSize * count)
}
return cpuCost + memoryCost + diskCost
}
// GetPlanCost calculates the cost of the plan if it has not been calculated yet and returns the cost.
func (p *PhysicalSort) GetPlanCost(taskType property.TaskType, option *PlanCostOption) (float64, error) {
costFlag := option.CostFlag
if p.planCostInit && !hasCostFlag(costFlag, CostFlagRecalculate) {
return p.planCost, nil
}
childCost, err := p.children[0].GetPlanCost(taskType, option)
if err != nil {
return 0, err
}
p.planCost = childCost
p.planCost += p.GetCost(getCardinality(p.children[0], costFlag), p.Schema())
p.planCostInit = true
return p.planCost, nil
}
// GetCost computes cost of TopN operator itself.
func (p *PhysicalTopN) GetCost(count float64, isRoot bool) float64 {
heapSize := float64(p.Offset + p.Count)
if heapSize < 2.0 {
heapSize = 2.0
}
sessVars := p.ctx.GetSessionVars()
// Ignore the cost of `doCompaction` in current implementation of `TopNExec`, since it is the
// special side-effect of our Chunk format in TiDB layer, which may not exist in coprocessor's
// implementation, or may be removed in the future if we change data format.
// Note that we are using worst complexity to compute CPU cost, because it is simpler compared with
// considering probabilities of average complexity, i.e, we may not need adjust heap for each input
// row.
var cpuCost float64
if isRoot {
cpuCost = count * math.Log2(heapSize) * sessVars.GetCPUFactor()
} else {
cpuCost = count * math.Log2(heapSize) * sessVars.GetCopCPUFactor()
}
memoryCost := heapSize * sessVars.GetMemoryFactor()
return cpuCost + memoryCost
}
// GetPlanCost calculates the cost of the plan if it has not been calculated yet and returns the cost.
func (p *PhysicalTopN) GetPlanCost(taskType property.TaskType, option *PlanCostOption) (float64, error) {
costFlag := option.CostFlag
if p.planCostInit && !hasCostFlag(costFlag, CostFlagRecalculate) {
return p.planCost, nil
}
childCost, err := p.children[0].GetPlanCost(taskType, option)
if err != nil {
return 0, err
}
p.planCost = childCost
p.planCost += p.GetCost(getCardinality(p.children[0], costFlag), taskType == property.RootTaskType)
p.planCostInit = true
return p.planCost, nil
}
// GetCost returns cost of the PointGetPlan.
func (p *BatchPointGetPlan) GetCost(opt *physicalOptimizeOp) float64 {
cols := p.accessCols
if cols == nil {
return 0 // the cost of BatchGet generated in fast plan optimization is always 0
}
sessVars := p.ctx.GetSessionVars()
var rowSize, rowCount float64
cost := 0.0
if p.IndexInfo == nil {
rowCount = float64(len(p.Handles))
rowSize = p.stats.HistColl.GetTableAvgRowSize(p.ctx, cols, kv.TiKV, true)
} else {
rowCount = float64(len(p.IndexValues))
rowSize = p.stats.HistColl.GetIndexAvgRowSize(p.ctx, cols, p.IndexInfo.Unique)
}
networkFactor := sessVars.GetNetworkFactor(p.TblInfo)
seekFactor := sessVars.GetSeekFactor(p.TblInfo)
scanConcurrency := sessVars.DistSQLScanConcurrency()
cost += rowCount * rowSize * networkFactor
cost += rowCount * seekFactor
cost /= float64(scanConcurrency)
if opt != nil {
setBatchPointGetPlanCostDetail(p, opt, rowCount, rowSize, networkFactor, seekFactor, scanConcurrency)
}
return cost
}
// GetPlanCost calculates the cost of the plan if it has not been calculated yet and returns the cost.
func (p *BatchPointGetPlan) GetPlanCost(_ property.TaskType, option *PlanCostOption) (float64, error) {
costFlag := option.CostFlag
if p.planCostInit && !hasCostFlag(costFlag, CostFlagRecalculate) {
return p.planCost, nil
}
p.planCost = p.GetCost(option.tracer)
p.planCostInit = true
return p.planCost, nil
}
// GetAvgRowSize return the average row size.
func (p *BatchPointGetPlan) GetAvgRowSize() float64 {
cols := p.accessCols
if cols == nil {
return 0 // the cost of BatchGet generated in fast plan optimization is always 0
}
if p.IndexInfo == nil {
return p.stats.HistColl.GetTableAvgRowSize(p.ctx, cols, kv.TiKV, true)
}
return p.stats.HistColl.GetIndexAvgRowSize(p.ctx, cols, p.IndexInfo.Unique)
}
// GetCost returns cost of the PointGetPlan.
func (p *PointGetPlan) GetCost(opt *physicalOptimizeOp) float64 {
cols := p.accessCols
if cols == nil {
return 0 // the cost of PointGet generated in fast plan optimization is always 0
}
sessVars := p.ctx.GetSessionVars()
var rowSize float64
cost := 0.0
if p.IndexInfo == nil {
rowSize = p.stats.HistColl.GetTableAvgRowSize(p.ctx, cols, kv.TiKV, true)
} else {
rowSize = p.stats.HistColl.GetIndexAvgRowSize(p.ctx, cols, p.IndexInfo.Unique)
}
networkFactor := sessVars.GetNetworkFactor(p.TblInfo)
seekFactor := sessVars.GetSeekFactor(p.TblInfo)
cost += rowSize * networkFactor
cost += seekFactor
cost /= float64(sessVars.DistSQLScanConcurrency())
if opt != nil {
setPointGetPlanCostDetail(p, opt, rowSize, networkFactor, seekFactor)
}
return cost
}
// GetPlanCost calculates the cost of the plan if it has not been calculated yet and returns the cost.
func (p *PointGetPlan) GetPlanCost(_ property.TaskType, option *PlanCostOption) (float64, error) {
costFlag := option.CostFlag
if p.planCostInit && !hasCostFlag(costFlag, CostFlagRecalculate) {
return p.planCost, nil
}
p.planCost = p.GetCost(option.tracer)
p.planCostInit = true
return p.planCost, nil
}
// GetAvgRowSize return the average row size.
func (p *PointGetPlan) GetAvgRowSize() float64 {
cols := p.accessCols
if cols == nil {
return 0 // the cost of PointGet generated in fast plan optimization is always 0
}
if p.IndexInfo == nil {
return p.stats.HistColl.GetTableAvgRowSize(p.ctx, cols, kv.TiKV, true)
}
return p.stats.HistColl.GetIndexAvgRowSize(p.ctx, cols, p.IndexInfo.Unique)
}
// GetPlanCost calculates the cost of the plan if it has not been calculated yet and returns the cost.
func (p *PhysicalUnionAll) GetPlanCost(taskType property.TaskType, option *PlanCostOption) (float64, error) {
costFlag := option.CostFlag
if p.planCostInit && !hasCostFlag(costFlag, CostFlagRecalculate) {
return p.planCost, nil
}
var childMaxCost float64
for _, child := range p.children {
childCost, err := child.GetPlanCost(taskType, option)
if err != nil {
return 0, err
}
childMaxCost = math.Max(childMaxCost, childCost)
}
p.planCost = childMaxCost + float64(1+len(p.children))*p.ctx.GetSessionVars().GetConcurrencyFactor()
p.planCostInit = true
return p.planCost, nil
}
// GetPlanCost calculates the cost of the plan if it has not been calculated yet and returns the cost.
func (p *PhysicalExchangeReceiver) GetPlanCost(taskType property.TaskType, option *PlanCostOption) (float64, error) {
costFlag := option.CostFlag
if p.planCostInit && !hasCostFlag(costFlag, CostFlagRecalculate) {
return p.planCost, nil
}
childCost, err := p.children[0].GetPlanCost(taskType, option)
if err != nil {
return 0, err
}
p.planCost = childCost
// accumulate net cost
if p.ctx.GetSessionVars().CostModelVersion == modelVer1 {
p.planCost += getCardinality(p.children[0], costFlag) * p.ctx.GetSessionVars().GetNetworkFactor(nil)
} else { // to avoid regression, only consider row-size on model ver2
rowSize := getTblStats(p.children[0]).GetAvgRowSize(p.ctx, p.children[0].Schema().Columns, false, false)
p.planCost += getCardinality(p.children[0], costFlag) * rowSize * p.ctx.GetSessionVars().GetNetworkFactor(nil)
}
p.planCostInit = true
return p.planCost, nil
}
func getOperatorActRows(operator PhysicalPlan) float64 {
if operator == nil {
return 0
}
runtimeInfo := operator.SCtx().GetSessionVars().StmtCtx.RuntimeStatsColl
id := operator.ID()
actRows := 0.0
if runtimeInfo.ExistsRootStats(id) {
actRows = float64(runtimeInfo.GetRootStats(id).GetActRows())
} else if runtimeInfo.ExistsCopStats(id) {
actRows = float64(runtimeInfo.GetCopStats(id).GetActRows())
} else {
actRows = 0.0 // no data for this operator
}
return actRows
}
func getCardinality(operator PhysicalPlan, costFlag uint64) float64 {
if hasCostFlag(costFlag, CostFlagUseTrueCardinality) {
return getOperatorActRows(operator)
}
return operator.StatsCount()
}
// estimateNetSeekCost calculates the net seek cost for the plan.
// for TiKV, it's len(access-range) * seek-factor,
// and for TiFlash, it's len(access-range) * len(access-column) * seek-factor.
func estimateNetSeekCost(copTaskPlan PhysicalPlan) float64 {
switch x := copTaskPlan.(type) {
case *PhysicalTableScan:
if x.StoreType == kv.TiFlash { // the old TiFlash interface uses cop-task protocol
return float64(len(x.Ranges)) * float64(len(x.Columns)) * x.ctx.GetSessionVars().GetSeekFactor(x.Table)
}
return float64(len(x.Ranges)) * x.ctx.GetSessionVars().GetSeekFactor(x.Table) // TiKV
case *PhysicalIndexScan:
return float64(len(x.Ranges)) * x.ctx.GetSessionVars().GetSeekFactor(x.Table) // TiKV
default:
return estimateNetSeekCost(copTaskPlan.Children()[0])
}
}
// getTblStats returns the tbl-stats of this plan, which contains all columns before pruning.
func getTblStats(copTaskPlan PhysicalPlan) *statistics.HistColl {
switch x := copTaskPlan.(type) {
case *PhysicalTableScan:
return x.tblColHists
case *PhysicalIndexScan:
return x.tblColHists
default:
return getTblStats(copTaskPlan.Children()[0])
}
}
// getTableNetFactor returns the corresponding net factor of this table, it's mainly for temporary tables
func getTableNetFactor(copTaskPlan PhysicalPlan) float64 {
switch x := copTaskPlan.(type) {
case *PhysicalTableScan:
return x.SCtx().GetSessionVars().GetNetworkFactor(x.Table)
case *PhysicalIndexScan:
return x.SCtx().GetSessionVars().GetNetworkFactor(x.Table)
default:
if len(x.Children()) == 0 {
x.SCtx().GetSessionVars().GetNetworkFactor(nil)
}
return getTableNetFactor(x.Children()[0])
}
}
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